The present invention relates generally to a method for reduction of iron ore concentrates into high purity elemental iron, and more specifically to an apparatus and method for direct reduction of iron ore concentrates utilizing metallic aluminum as a reductant material. It has been known that oxidation-reduction reactions may be undertaken utilizing elemental metals selected from differing electromotive activity. In this manner, therefore, direct reduction of certain ores, particularly iron ore concentrates, may be undertaken through oxidation-reduction reactions including iron compounds and metallic aluminum.
The method and apparatus of the present invention produces iron of high purity from iron ore concentrates. The method is self-generating, and in view of the exothermic nature of the reaction, external fuel is not required. Normally, within a confined vessel, reaction temperatures exceed 5000.degree. F. In accordance with the reaction, the immediate products are molten aluminum oxide--silicon oxide refractory slag along with molten iron of high purity. The high purity iron is withdrawn from the reactant vessel along or through a tapping port disposed at a first and lower axial disposition or location, and molten slag is tapped from a port disposed above the metal tapping port.
Iron recovery typically exceeds 99% for stoichiometric mixtures, with analysis of the iron product showing less than 0.01 weight percent carbon and less than 0.005 weight percent of all other individual elements normally analzyed spectrographically. These individual elements normally include manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, copper, aluminum, titanium and magnesium.
The basic stoichiometric equations for the direct reduction of common iron oxides found in iron ore concentrates are as follows: EQU 8Al(s)+3Fe.sub.3 O.sub.4 (s).fwdarw.9Fe(l)+4Al.sub.2 O.sub.3 (l)
or EQU 2Al(s)+Fe.sub.2 O.sub.3 (s).fwdarw.2Fe(l)+Al.sub.2 O.sub.3 (l)